A data carrier which includes an electrical module and which can be used over a prolonged period of time is to be found for example in WO-A-92/21105, wherein parts which are essential for the user, of the data contained in the electronic module can be represented in the heat-sensitive coating on the card body and can no longer be removed. Heat-reversible coatings and data carriers in card form which include same are known for example from EP-A-174 902 or EP-A-344 789. In that case the erasing temperature range is generally between 50.degree. and 100.degree. C. and the writing operation is effected at temperatures above 110.degree. C. Writing on the heat-sensitive coating can thus be erased and re-applied.
An apparatus of the kind set forth in the opening part of this specification is known for example from EP-B-199 234. The thermal print head is rigidly arranged on the transport path and the oppositely disposed backing roller is resiliently movably suspended. For reversible processing of a thermal coating, above-mentioned EP-A-174 902 and EP-A-344 789 each diagrammatically show apparatuses in which the single thermal print head is heated to the respectively required writing or erasing temperature. In that respect the thermal print head was intended to perform two different functions: for erasing written characters, it is desirable if the entire surface to be processed is set to the erasing temperature, as uniformly as possible. In contrast, the writing operation is possible only by virtue of heating of the heat-sensitive coating being effected in an only locally delimited manner, namely within the contours of the characters to be reproduced.